<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
  <script>
    //map
    Array.prototype.myMap=function(fn){
      const newArr=[]
    for(let i=0;i<this.length;i++){
     newArr.push(fn(this[i],i,this)) 
      }
   return newArr
    }
    const arr=[1,2,3,4,5,6]
   console.log(arr.myMap((item)=>{
       item+1
    })); 

    //filter
    Array.prototype.myFilter=function(fn){
      const newArr1=[]
      for(let i=0;i<this.length;i++){
      fn(this[i],i,this)&&newArr1.push(this[i])
      }
      return newArr1
    }
   console.log(arr.myFilter((item)=>{
      return item>3
    })); 
  </script>
</body>
</html>